Many surgical procedures require that a patient's body part, such as a limb, portion of a limb, extremity, organ or tissue be positioned in a number of different positions for the performance of a surgical procedure. It is desirable that the operating surgeon or surgical assistant be able to move the limb or other body part into other positions and configurations that may be required during the course of the surgical procedure. It is also desirable that any positioning apparatus that may be used to achieve such positions and configurations not obstruct the surgical site, and be able to avoid any obstacles that may exist around the surgical site, such as medical imaging systems, operating room lights, instrument trays, or other apparatus.
Various methods for positioning and supporting a patient's limb or body part are known in the prior art. One common method for positioning a body part is to have a sterile surgical assistant hold the body part in a desired position, and change the position when and as requested by the operating surgeon. This task is fatiguing for the surgical assistant, and this technique may not support the patient's body part in a sufficiently precise and rigid manner for the surgical procedure. Other typical methods for positioning a patient's limb are to rest the limb on a table for that purpose, to hang the limb over part of the operating room table, or to rest the limb on the lap of a seated operating surgeon. All of these techniques offer a very limited range of possible limb configurations, serve to restrict the movement of the surgeon, and result in reduced precision and rigidity of support.
In addition to the methods for positioning illustrated above, apparatus for supporting and positioning body parts exists in the art. One common supporting means consists of slings attached to the patient's limb, ropes and occasionally weight, which are hung over or tied to operating room light fixtures, intravenous fluid support stands, or other operating room fixtures, in order to suspend the limb (e.g. see Herschman, Z. J., Frost, E. A. M. Goldiner, P. L.; Pulse Oximetry during Shoulder Arthroscopy, Anesthesiology, 65:565-566, 1986). These types of supporting means are difficult to set up and take down, clumsy to adjust, and often obstruct the surgical site. Furthermore, adjusting such apparatus to achieve a new position may require the assistance of a non-sterile person, in that operating room fixtures and support stands that may require re-positioning are not considered sterile, hence cannot be touched by a surgeon. This may preclude optimal positioning of the limb or body part, as the surgeon may no longer have direct control over the final position of the limb or body part.
Additional specialized positioning devices for supporting limbs or body parts are known in the prior art. One class of positioning device includes a wide variety of devices for holding a patient's leg in position for arthroscopic knee surgery. Such devices generally grip the patient's leg near the foot, and also at the thigh. Means are provided to allow the surgeon to move the lower leg into various configurations suitable for arthroscopic surgery, while the upper part of the leg is held in a fixed position. Such devices are suitable only for surgery at or near the knee, and are not suitable for use during preparation of the limb for surgery. In addition, these devices cannot be positioned so as to avoid obstacles near the surgical site, may obstruct the surgical site, do not offer any means for detaching the grasping means and attaching another grasping means for grasping another body part, and are difficult to drape to establish a sterile barrier between the surgical site and the patient's limb while it is grasped by the positioning device.
In an attempt to overcome the drawbacks of existing devices for holding retraction devices during surgery, the Elmed Company of Addison Illinois manufactures a multi-jointed mechanism, the "Elmed Retract-Robot", catalog number 15088-00 single arm instrument, which can be locked in a wide range of positions with a thumbscrew arrangement. This device, although not intended for manipulation of all limbs and body parts, could perhaps be adapted with appropriate grasping means to solve some of the problems heretofore described. However, such a device, even if configured with an appropriate grasping means, would still not be suitable for a wide range of surgical procedures, as the device does not provide a sufficiently large range of motion for many such procedures. It is conceivable that several such devices could be connected together to create a larger structure with an increased range of motion, but such a structure would be very difficult to reposition, in that each device in the structure would have to be unlocked, positioned and locked individually each time a new position is required. In addition, it is unlikely that several such devices connected together would offer sufficient strength to support a patient's leg or arm, there is no convenient way for a grapsing means to be detached and replaced with another grasping means for grasping a different body part, and the device is difficult to drape to establish a sterile barrier between the surgical site and the patient's limb while the limb is grasped by the positioning device, hence the device would typically be sterilized before each use, which is time consuming and costly.
Also known in the art is a similar retraction device, widely known by surgeons throughout the world as a "Greenberg" brain retractor. This retraction device consists of a plurality of ball and socket joints, threaded upon a length of cable. This cable may be tightened with a lever mechanism to increase the friction between each ball and socket joint. The Greenberg brain retractor is not suitable for manipulation of a wide range of limbs due to its typically small size. In addition, the strength of the ball and socket joints when fully locked is insufficient to support the loads typically expected when positioning a patient's limb, there is no convenient way for a grasping means to be detached and replaced with another grasping means for grasping a different body part, and the device is difficult to drape to establish a sterile barrier between the surgical site and the patient's limb while the limb is grasped by the positioning device, hence the device would typically be sterilized before each use, which is time consuming and costly.
One problem that is common to any means of supporting a patient's limb or body part is that of establishing a suitable sterile barrier between a surgical site and a patient's limb part while it is being supported by such supporting means. The patient's limb, the supporting means, the supporting point to which the supporting means is connected, and the patient's body form a closed annular shape. This closed annular shape is usually established when the patient's limb is connected to the supporting means to hold the limb in position for preparation of the surgical site. It is undesirable to detach the patient's limb from the supporting means to apply a sterile surgical drape to the limb or supporting means after the surgical site is prepared, as this may contaminate the prepared surgical site. It is also undesirable to cover the limb and supporting means with sterile drapes before the surgical site is prepared, as the solutions used for preparation may contaminate the drape.
One method of draping such an annular shape is to drape flat sterile sheets over the limb and supporting mechanism, and fasten the drapes in position with sterile clips or tape. This may leave openings in the drape, compromising the integrity of the sterile barrier, and will usually leave a large amount of excess drape hanging from the limb and supporting means, such that it may obstruct the surgical site.
A preferred form of sterile cover for such an annular shape consists of an elongated flexible tube, made of an impervious sterile material such as a flexible thermoplastic, which is placed over the limb and supporting mechanism to act as a sterile sleeve. Such a sleeve may be considered to be a torus, where a torus is defined by the Oxford English Dictionary as "a surface generated by the rotation of a plane closed curve about an axis lying in its plane, but not intersecting it." The draping problem can thus be described as a need to interlink a toroidal sterile drape with a closed annular shape, in which the annular shape, when first closed, is considered to be nonsterile or contaminated.
Although many examples of sterile drapes in the form of a elongated flexible tube or torus are known in the art, none provide a means so that such a sterile drape can be interlinked with a nonsterile or contaminated limb or supporting structure without contaminating the drape.
The following U.S. patent application of the applicants is more or less relevant to the subject matter of the applicants' invention.
U.S. application filed Feb. 19, 1986, continuation-in-part, Ser. No. 831,001; Title: Advanced Medical Robot; Inventors: James Allen McEwen et al.